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Topic: Engine rebuild (Read 1645 times)

Fellow Enfield owners, greetings. As a young motorcycle enthusiast with little knowledge any advice you can give me would be much appreciated :-)

Forgive me if ive posted in the wrong section of the site.

I've owned a 500 bullet for just under a year now which whilst i love it has caused me nothing but problems.

The latest is what I believe to be something to do with the piston rod, piston, big end damaged. I was accelerating (perhaps a little too hard) on a cold day in first and the engine started to make a horrendous tapping noise, power immediately cut out and I lost all compression.

Luckily I pulled over next to a door man who was a handy mechanic and he took the spark plug out and stuck a screwdriver in the whole and discovered the piston wasn't moving.

I've stuck so much money into it so far that I really want to try and rebuild the engine myself. This will be my first attempt at anything like this but I've changed throttle, clutch, break cables etc so my belief is, perhaps a little naively, that with a good workshop manual I can learn on the job. My father's friend is a handy mechanic and has just retired so I'm hoping he will let me do it in his workshop and offer me some assistance.

a. If anyone has anyone has experience any similar issues like this. b. Do you think this achievable, bearing in mind i have little mechanical knowledge although I can pick things up easily and like a challenge.c. What's the best manual to use, I have a copy of Pete Snidal's workshop manual. d. What are peoples thoughts on picking up parts on eBay from India. Gasket sets (not original) are so much cheaper on eBay than from dealers but I'm wondering if they're not e. If you can point me in the direction of a blog/ forum page that offers advice for similar symptoms or engine rebuild.

We can't really help you until we know what exact bike you have, as the different models have their own quirks and issues. But from what you've described it sounds like you broke the connecting rod. It's possible when this happens to have major damage to the internals of the engine. Tell us what year and model you have and we can point you in the right direction.

If you have an ES model the problem will likely be your sprag clutch has grenaded and has jammed things up. If you do have an ES you should take your primary cover off and have a look inside. This is a very common problem and is easy to fix.

The people here can help you figure it out, and help you with what to do.I have been involved with more Bullet rebuilds than I can remember, and that's a lot. So, you can do it, and there are experienced people here to help.

Regarding parts, I think gaskets and stuff like that are fine to get from India, but get them from a highly rated vendor.As for internal engine parts, they weren't good when the bike was built, and putting the same junk back in isn't a good idea. Upgrade any broken part, and upgrade the key parts which are known to fail.

If you have an ES model the problem will likely be your sprag clutch has grenaded and has jammed things up. If you do have an ES you should take your primary cover off and have a look inside. This is a very common problem and is easy to fix.

Did you read what he said? It happened under acceleration in 1st gear not when starting the engine with the electric start.

They turned the engine over & the piston's not going up & down. That's the problem.

Did you read what he said? It happened under acceleration in 1st gear not when starting the engine with the electric start.

They turned the engine over & the piston's not going up & down. That's the problem.

It doesn't hurt to see if it might be something that is not catastrophic. I have been in his shoes and can say it is the last thing you want happening. But on a positive note he is at the right place to get the advise he needs.

OK - Thanks everyone, all and any advice is much appreciated. Once I've spoken to my dad's friend and asked him about repairing at his i'll open her up and let you know how I get on.

Any advice on workshop manuals?

james

I advise you to get the complete technical package from our hosts at NFIELD Gear. 3 texts, including th factory parts book, factory service manual, and Pete Snidal's book. Between all 3 of them, and asking questions here, you should get through it.

Oh My God! That poor freaking head! Have they never heard of using the right tool for the job!? Now pry bar, no dead blow?! Did anyone else notice the massive gouge he put into the head mating surface trying to beat and pry that head off at 3:10? I hope he plans on decking the head now.

Oh My God! That poor freaking head! Have they never heard of using the right tool for the job!? Now pry bar, no dead blow?! Did anyone else notice the massive gouge he put into the head mating surface trying to beat and pry that head off at 3:10? I hope he plans on decking the head now.

Scottie J

I started watching these videos of Indian bike shops years ago & I'm continually amazed. And the cringe factor during some of them is 100%.

But then there are also some videos of the gorgeous restoration work that comes out of some of these hole-in-the-wall shops. It's amazing.

If anyone has not seen it, find the video of the guy who pin-stripes the gold on the gas tanks. He's the Indian Von Dutch of Enfields & he is deadly serious.

Thanks for all your tips. To let you know. I took the head off and it was the piston that had shattered. I have bought a new one and am in the midst of replacing the old one.

There are quite a few shards of the metal including bits of broken piston ring that have however come and are swimming in the sump. Ive bought an extendible magnet which has managed to pick up a fair bit of the metal however I was wondering if anyone had any other techniques for getting the metal shards out. Perhaps I could drain them out? or rinse them out with water?

Unfortunately, there's not an easy way to clear the sump of metal.Short of a complete disassembly, I have heard of people taking the engine out of the bike, and filling up the sump with kerosene, and shaking it around, and then turning it upside down and pouring it out. Repeat until no more metal appears to be coming out.

Depending upon where some of the metal got to before the engine stopped, don't be too surprised if you see some main bearing failure in the not too distant future.

Hte first engine I totally tore down and rebuilt was a BSA Gold Star, essentially the same as a Bullet. It's not terribly hard, but you will need a new Crankshaft, rod bearing and rod in an upgraded mode. these assemblys are available assembled, which is the way to go. I had to assemble my BSA Crank. The rest of the stuff, main bearings, piston and such are going to be dependent on what shape the original parts are in. You need to tear the engine down and see what parts are ruined.While you're doing this disassembly, take copious pictures so you can see/remember where everything goes! It'll help immensely. This means from when you start to take the engine out, through engine disassembly. You really don't want any parts left out when you think you're done!Bare

Yeah. If your piston exploded you most likely need to do a complete tear down and rebuild, and don't order any parts until you have it completely disassembled and you know exactly what you need. When a piston grenades like that you are almost guaranteed to need to replace everything. Also, I bet your cylinder is going to need reboring as well with the addition of an over-sized piston, I'm sure you have nasty gouges all over the cylinder wall. Just replacing the piston without additional work will cause low compression and bad oil consumption. Basically a waste of your time.

Can post some pics of the carnage so we can see what exactly happened?

Also, pistons are not made of steel so a magnet isn't going to get any of those chunks out of there anyways.